martes, 23 de octubre de 2012

The Conversation Edu Au * Asteroid mining

There will be a future mining boom, as heralded in recent media stories. But this mining will take place in a location even more hostile than the Australian Outback – space.

More specifically, the ore bodies that comprise the myriad asteroids we now know are whizzing by our planet with alarming frequency.

The publicity blitz was provoked by the formation of a new US-based company, named Planetary Resources.

The company is backed by film director James Cameron and a host of well-known billionaires who made their fortunes in the aerospace and internet industries.

Planetary Resources hasa seemingly unlikely aim, yet one that has been obvious to space scientists for at least 20 years: to mine near-Earth asteroids, which are composed of a wide variety of useful minerals.

One thing perhaps not made clear in the media furore, is thepoint of this mining. It’s not to divert the asteroids and bring them down to the surface of our planet, but rather to make use of their valuable constituents for utilisation in space.

When humankind starts its move off the earth we’ll need to start manufacturing various products in space, including high-quality alloys and electronics. On the larger scale we’ll also need to construct large, permanently inhabited off-planet islands and it will be near-Earth asteroids from which we derive the needed raw materials.

The reason for this is not a shortage of minerals and other necessary supplies down here on Earth, but rather the expense of getting them into space.

To get a rocket off Earth’s surface and into orbit we need to accelerate it to a speed of over 7.5km per second (or27,000km/h). That is expensive, although launch costs have dropped in recent years to about US$10,000 per kilogram.

A cubic metre of water may cost you a few dollars from your bathroom tap, but the same volume would cost US$10 million to put into orbit. In fact, the cost would be even higher than that, due to the weight of the container needed to hold the water.

To send payloads further away, escaping Earth’s gravity and going into independent orbit around the sun, requires more energy still (and therefore more money).